Subcool, Fluid Productivity, and Liquid Level Above a SAGD Producer
- Jian-Yang Yuan (Osum Oil Sands Corporation) | Daniel Nugent (Osum Oil Sands Corporation)
- Document ID
- Society of Petroleum Engineers
- Journal of Canadian Petroleum Technology
- Publication Date
- September 2013
- Document Type
- Journal Paper
- 360 - 367
- 2013. Society of Petroleum Engineers
- 5.3.9 Steam Assisted Gravity Drainage, 5.1.1 Exploration, Development, Structural Geology
- 3 in the last 30 days
- 466 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
Thermodynamic steam-trap control, or subcool control, in a typicalsteam-assisted gravity-drainage (SAGD) production is essential to the stabilityand longevity of the operation. It is achieved commonly through the control offluid production. The goal of such control is to maintain a steady and healthyliquid production without allowing steam from the injector to bypass to theproducer. Therefore, it is effectively a control of the liquid level above theproducer. Unfortunately, it is not practical to monitor this liquid level. Arule-of-thumb subcool-per-metre estimation of 10°C/m of liquid level is popularin the industry; however it does not prove to hold in many situations. Thispaper presents a study of the dynamics of SAGD-production control with aresulting algebraic equation that relates subcool, fluid productivity, andwellbore drawdown to the liquid level above a producer. The main conclusions ofthis study include
- There is no minimum subcool value for a pure-gravity-drainage scenario;however, as the wellbore drawdown is considered, there is a minimum subcoolvalue in order to maintain the stability of fluid flow.
- For a given productivity, the liquid level increases as subcool increasesor as wellbore drawdown decreases.
- For each given set of operating parameters, there exists a criticalproductivity below which SAGD operation would halt.
- Before the steam chamber reaches the top of the reservoir, the fluidproductivity is limited by the vertical distance between the injector and theproducer; the larger the distance, the higher the fluid production rate canbe.
A verification of this analysis was conducted by a series of numericalreservoir simulations. Although limited to two dimensions, we expect that thisanalysis captures the main physics amid the dynamic complexity ofSAGD-production control. The resulting algebraic equation can be used forbetter understanding of the dynamics of subcool control and for determiningoperation strategies.
|File Size||1 MB||Number of Pages||8|
Butler, R.M., Bharatha, S., and Yee, C.T. 2000. Natural and Gas-liftin SAGD Production Wells. J Can Pet Technol 39 (1).PETSOC-00-01-01. http://dx.doi.org/10.2118/00-01-01.
Das, S. 2005. Improving the Performance of SAGD. Presented at theSPE/PS-CIM/CHOA International Thermal Operations and Heavy Oil Symposium,Calgary, 1-3 November. SPE-97921-MS. http://dx.doi.org/10.2118/97921-MS.
Edmunds, N. 2000. Investigation of SAGD Steam Trap Control in Two and ThreeDimensions. J Can Pet Technol 39 (1): 30-40.PETSOC-00-01-02. http://dx.doi.org/10.2118/00-01-02.
Gates, I.D. and Leskiw, C. 2010. Impact of steam trap control on performanceof steam-assisted gravity drainage. J. Pet. Sci. Eng. 75(1-2): 215-222. http://dx.doi.org/10.1016/j.petrol.2010.11.014.
Gotawala, D.R. and Gates, I.D. 2009. SAGD Subcool Control with SmartInjection Wells. Presented at the EUROPEC/EAGE Conference and Exhibition,Amsterdam, 8-11 June. SPE-122014-MS. http://dx.doi.org/10.2118/122014-MS.
Gotawala, D.R. and Gates, I.D. 2012. A Basis for Automated Control of SteamTrap Subcool in SAGD. SPE J. 17 (3): 680-686.SPE-159170-PA. http://dx.doi.org/10.2118/159170-PA.
Kisman, K.E. 2003. Artificial Lift--A Major Unresolved Issue for SAGD. JCan Pet Technol 42 (8): 39-45. PETSOC-03-08-02. http://dx.doi.org/10.2118/03-08-02.
Valk, P.A.V. and Yang, P. 2007. Investigation of Key Parameters in SAGDWellbore Design and Operation. J Can Pet Technol 46 (6).JCPT Paper No. 07-06-02. http://dx.doi.org/10.2118/07-06-02.